[BUG] Traceback during start on fresh Debian 13 install

[finndavid-univention]

• My issue is related to Add Water, the standalone installer app, and is not related to the Firefox GNOME Theme.

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Describe the bug
AddWater won't launch on a fresh Debian 13 installation and throws a traceback.

To Reproduce
Steps to reproduce the behavior:

1. Install Debian 13
2. Do a minimal GNOME install (without recommended packages)
3. Install Firefox from flathub
4. Install AddWater from flathub
5. Launch AddWater

Expected behavior
AddWater launches and finds the firefox profile folder.

Screenshots

Technical Details (please complete the following information):

 - Distribution: Debian 13
 - Desktop environment: GNOME 48 (minimal install)
 
 - Add Water version: 1.2.7
 - Add Water package format: Flatpak
 - Theme version: 

 - Browser name: Firefox
 - Browser package format: Flatpak
 - Browser version: 147.0

Additional context
Looks like flatpak Firefox changed the profile folder location from
~/.var/app/org.mozilla.firefox/.mozilla/firefox
to
~/.var/app/org.mozilla.firefox/config/mozilla/firefox
I added both paths via Flatseal to the allowed filesystem paths. I even allowed ALL paths beneat ~ to be allowed.
But it didn't change a thing, it always throws the traceback.

Attach log file if necessary
See screenshot above.

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• I have included enough relevant information to solve my problem.